Drupthob Thangtong Gyalpo visited Bhutan for the first time in 1433. He left a lasting spiritual legacy in the colourful narrative of a powerful Yogi who roamed the country performing sacred ceremonies in lhakhangs and revealing hidden treasures, or terma. He constructed a small chhorten at Dzondrak Gompa and a chorten-shaped monastery in the middle of the Paro valley called Dumtseg Lhakhang declaring that, hence-forth, the valley would be free of leprosy.
Having initially come to collect iron ore, the Great Chagzampa saw that Bhutan was in need of bridges over its precipitous gorges and fast flowing rivers, even more so than Tibet. He commandeered a team of blacksmiths to mould weighty chains and constructed bridges throughout the country.
His first bridge traversed the Paro Chhu and offered convenient access to Tachog Lhakhang Dzong, a lhakhang that he himself established. Although the original bridge was washed away in floods in 1969, some of the original chain links as well as iron from other bridges constructed by Thangtong Gyalpo were used to erect a replacement in 2005. This bridge is still a landmark, about five kilometres before the Chuzom checkpost on the Paro-Thimphu highway.
From Paro, the great yogi travelled to Wangdue Phodrang valley, where he received a donation of 250 pieces of iron from a local lama with which he constructed a bridge near Hesothangkha village.
During his second visit to Bhutan, in the 1440s, Thangtong Gyalpo visited the eastern part of the country where he first constructed a 100-metre bridge below the present-day Tashigang Dzong. Later, he also built bridges at Doksum in Tashigang, Dagme in Mongar, and at Khoma in Lhuentse.
Of the eight bridges built in Bhutan by the Great Chagzampa, Tachog Chakzam in Paro, Doksum Chakzam in Tashigang, Dangme Chakzam in Mongar, and Khoma Chakzam in Lhuentse still exist offering passage to pedestrians.